Paddlefish: Ecological, Aquacultural, and Regulatory Challenges of Managing a Global Resource

Abstract

<i>Abstract</i>.—The North American Paddlefish <i>Polyodon spathula</i> was first introduced into China from the United States in 1988, with the importation of 3,000 larvae. From this and subsequent introductions, successful spawning of broodstock raised in China was first achieved in Hubei Province in 2001. As of 2018, this nonnative Paddlefish is cultured in more than 10 provinces, including Hubei, Sichuan, and the southern area of Shaanxi, all throughout the Yangtze River basin, and Guangdong, in the Zhujiang River basin. Four large Paddlefish hatcheries with other, smaller, newly-established facilities produce about 10 million fingerlings per year. With feeding habits of Paddlefish being similar to those of Bighead Carp <i>Hypophthalmichthys nobilis</i>, a traditional fish species produced by Chinese aquaculture, fish farmers rear Paddlefish as a substitute species for Bighead Carp in their production systems. Typically, Paddlefish fingerlings (10 cm TL) are cultured to market sizes (0.6–0.75 kg) in ponds or cages in reservoirs. Paddlefish in China are cultured primarily for meat rather than roe. Acceptable market size can be reached within six months on prepared diets, whereas it takes one year on natural diet. Paddlefish are usually marketed live, as no processing industry has developed. Because Paddlefish have a low tolerance to hypoxia, long distance transportation of live market size Paddlefish is relatively limited. A few Paddlefish are also marketed as aquarium fish. Because of the limited supply of fingerlings and the difficulty of efficiently catching Paddlefish from large bodies of water, reservoir ranching as a production system has not been well developed. Also, reservoir ranching for Paddlefish was slowed due to concerns about potential hybridization between the nonnative Paddlefish and the critically endangered Chinese Paddlefish <i>Psephurus gladius</i> of the Yangtze River. The short supply and high price of fingerlings remain major factors limiting the expansion of North American Paddlefish production in China.